readme: Add AppVeyor build status badge/link
diff --git a/README.md b/README.md
index 2187c7f..ec74f23 100644
--- a/README.md
+++ b/README.md
@@ -2,6 +2,7 @@ libgit2 - the Git linkable library
==================================
[](http://travis-ci.org/libgit2/libgit2)
+[](https://ci.appveyor.com/project/nulltoken/libgit2/branch/master)
[](https://scan.coverity.com/projects/639)
`libgit2` is a portable, pure C implementation of the Git core methods